The term User Experience has become mainstream. But what is an experience? In this paper I will give a definition of the concept, explaining it within the paradigm of evolutionary psychology. I will briefly describe its main components (executive functions, episodic and semantic memory), mechanisms (learning, reinforcement, evaluation), and goals (the motivational system and the inclusive fitness).
Finally, I will provide some reasons of the usefulness of an explicit definition of experience, both within an academic context and the design and business practice.